Toyota today promised to slash carbon emissions from its new Prius hybrid model by more than a third, laying down the gauntlet to its rivals to make a greener – and more affordable – car.Speaking at the Frankfurt motor show, executives from the Japanese car maker also dismissed new "pure electric" models being developed by European competitors Peugeot and Renault/ Nissan as too expensive and impractical.

This year's motor show – the largest industry event in the world – has been dominated by the electric car as executives are forced by environmental pressures to find an alternative to the traditional combustion engine model.

Toyota is launching a new "plug-in" version for its hugely successful hybrid Prius model, which combines a combustion engine with an electric motor to reduce its emissions. The plug-in version – due to be trialled in the UK next year – will reduce emissions from the Prius's current 89g of carbon dioxide per kilometre to 60g or less. This version allows owners to charge up the car's battery at home and to run the car on electric battery alone for short distances.

Like its Japanese rival Honda, Toyota is sceptical about the appeal of "pure electric vehicles (EVs)", which are powered solely by electric batteries. These are potentially much more expensive than hybrid models and have a shorter range.

Graham Smith, senior vice president for Toyota Motor Europe, said: "We see a fairly challenging road ahead for the electric vehicle. Up to now, motorists have had only one task all their lives – find a station and fill up with gas. For EVs, people have to get their heads round charging their car for several hours a night – do they even have a plug outside their house?"

Peugeot is developing its own hybrid model but admits it faces a big challenge in taking on Toyota, which dominates the market. Chief executive Philippe Varin argues that all the technologies being developed, including EVs, have their own risks. "There are a lot of uncertainties. We don't want to put all our eggs in one basket. It depends on a lot of things – how the battery technology develops, how consumers react, and price."

Opel/Vauxhall has seized on what it believes to be a gap in the market. It believes motorists have "range anxiety" about electric cars, fearing that the juice will run out and leave them stranded on a dark country lane. Its Ampera is charged in the normal way but has a petrol engine that kicks in when its maximum range of 40 miles on its electric battery is exceeded.